[PATCH] serial: digicolor: fix use-after-free on driver unbind

[Junrui Luo]

The digicolor_uart_console_write() function accesses the global
digicolor_ports[] array to retrieve the uart port pointer, which
can lead to a use-after-free if the console write occurs after
the port has been removed via unbind.

digicolor_uart_remove() leaves a dangling pointer in the array.

Fix by clearing the array entry in digicolor_uart_remove() and
adding a NULL check in digicolor_uart_console_write().

Reported-by: Yuhao Jiang <danisjiang at gmail.com>
Reported-by: Junrui Luo <moonafterrain at outlook.com>
Fixes: 5930cb3511df ("serial: driver for Conexant Digicolor USART")
Signed-off-by: Junrui Luo <moonafterrain at outlook.com>
---
 drivers/tty/serial/digicolor-usart.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/tty/serial/digicolor-usart.c b/drivers/tty/serial/digicolor-usart.c
index d2482df5cb9b..5861be2072c4 100644
--- a/drivers/tty/serial/digicolor-usart.c
+++ b/drivers/tty/serial/digicolor-usart.c
@@ -397,6 +397,9 @@ static void digicolor_uart_console_write(struct console *co, const char *c,
 	unsigned long flags;
 	int locked = 1;
 
+	if (!port)
+		return;
+
 	if (oops_in_progress)
 		locked = uart_port_trylock_irqsave(port, &flags);
 	else
@@ -508,6 +511,7 @@ static void digicolor_uart_remove(struct platform_device *pdev)
 	struct uart_port *port = platform_get_drvdata(pdev);
 
 	uart_remove_one_port(&digicolor_uart, port);
+	digicolor_ports[port->line] = NULL;
 }
 
 static const struct of_device_id digicolor_uart_dt_ids[] = {

---
base-commit: ea1013c1539270e372fc99854bc6e4d94eaeff66
change-id: 20251222-fixes-74e6b26513d1

Best regards,
-- 
Junrui Luo <moonafterrain at outlook.com>